Rotary piston internal combustion engine

ABSTRACT

An internal combustion engine designed to convert thermal energy into mechanical energy according to the same general principle employed in conventional reciprocating piston-and-cylinder combustion engines, wherein the equivalent of the cylinder of the conventional engine is replaced by two series of chambers, a first series and a second series, each series of chambers being separately disposed in a circumferential arrangement about a common axis and separated in space one from another and wherein the conventional piston is replaced by one or more vanes, said vanes being adapted to form sealing contact with the chambers and the two series of chambers being connected by one or more transfer ports wherein air is compressed in one series of chambers and combustion gasses are exhausted by means of the other series of chambers.

FIELD OF THE INVENTION

The present invention relates to a new design of internal combustionengine.

BACKGROUND TO THE INVENTION

The internal combustion engine is widely used as a means of convertingthermal energy into mechanical energy. It has been developed extensivelyover the past few decades, especially by motor vehicle manufacturers,into a compact, lightweight and efficient unit.

However, the principle of a reciprocating piston connected by means of aconnecting rod to a crank shaft and constrained within a cylinder hasinherent drawbacks. The piston, by the very nature of its function, hasa significant mass and thus inertia. Consequently, the reciprocatingmotion causes vibration and also limits the maximum possible speed ofrotation of the crank shaft.

The standard reciprocating engine, as used in automobiles, has both arelatively small mechanical efficiency and fuel efficiency. One reasonfor this is the short stroke of the engine. The limited amount of timepossible for the power stroke leads to incomplete detonation. Theinefficiency increases with engine speed because the time for combustionis correspondingly reduced.

Another disadvantage of the conventional piston engine results fromvalve overlap. Since both exhaust and intake valves are open at the sametime, a proportion of the air/fuel mixture is exhausted unburnt. Thethermal efficiency of the reciprocating engine is also considerably lessthan optimal. Detonation occurs before top dead center and so expansionof the gases causes the mixture to heat up rather than to provide workenergy.

One further drawback is that the power stroke and the compression strokeare an identical length for any given piston. Since power is onlyderived on the exhaust or power stroke of the engine cycle, theefficiency of an engine could be improved by lengthening this part ofthe cycle. Although theoretically possible, the design of a conventionaltwo stroke or four stroke engine does not lend itself to this.

Many attempts have been made to minimize or obviate these inherentdisadvantages. The WANKEL (TM) or rotary piston engine is probably themost well-known of these, where a rotating piston is used to rotate ashaft and thus generate motive power. In this modification, the edges ofa rotating piston open and close ports in a cylinder wall, so that thepiston itself controls the "breathing" of the engine, without the aid ofvalves. The piston is substantially triangular in shape with convexsides and rotates in a cylinder whose internal cross-section has asubstantially oval shape slightly constricted in the middle(epitrochoid). When the piston rotates, seals mounted at its threecorners continuously sweep along the wall of the cylinder. The threeenclosed spaces formed between the piston and the wall successivelyincrease and decrease in size with each revolution. These variations inthe spaces are utilized for drawing in the fuel-and-air mixture, forcompressing this mixture, for combustion, and for discharging the burnedgases. In this way, the full four-stroke working cycle is performed.

It will be appreciated that in the rotary piston engine there are noreciprocating masses which have to be alternatively accelerated anddecelerated and the forces or inertia associated with the reciprocatingmotion are therefore obviated in this type of engine. As a result,higher speeds of rotation are theoretically possible.

However, one of the major problems in the construction of the rotarypiston engine is the sealing of the three spaces in relation to oneanother. Intercommunication between these spaces would be detrimental tothe proper functioning of the engine. This problem has been partlysolved by means of a system of sealing strips.

However, the problem of wear and durability has only been partlyresolved and as a consequence, these rotary engines have yet to finduniversal acceptance.

Many attempts have been made to improve the WANKEL engine, the mostrelevant of these known to the applicant being described in U.S. Pat.No. 4,401,070 (McCann). This describes an engine with a rotor and atleast one vane extending slidably through the rotor in a transversedirection for rotation therewith. The vane has opposite ends extendiblebeyond the rotor, which itself rotates within a stator which has ahollow, cylindrical interior. The stator has opposite side walls withcircumferentially extending depressions therein, the depressions of theopposite walls being staggered, causing transverse reciprocation of thevane as the rotor is rotated. The depressions are shaped to slidablyreceive the ends of each vane in sealing contact.

The stator is in effect two static housings which embrace the rotor andsupport it at either end of a rotor shaft. The housings contain twocavities formed in their ends into which the rotor plus sliding vanesfit.

This design relies upon a relatively complex series of ducts and holdingvolumes to transfer an aliquot of compressed gas from one side of a vaneduring the compression cycle to the reverse side of the same vane forthe power stroke. This not only exacerbates the sealing problemsinherent with this type of engine but requires complex machining duringmanufacture. It also means that cavities on each side of the rotor areused for compression and power strokes alternately.

It is therefore an object of the present invention to provide a new kindof internal combustion engine which does not suffer from thesedisadvantages.

SUMMARY OF THE INVENTION

According to the first aspect of the invention, in its broadest sense,there is provided an internal combustion engine, designed to convertthermal energy into mechanical energy according to the same generalprinciple employed in conventional reciprocating piston-and-cylindercombustion engines, wherein:

(i) the equivalent of the cylinder of the conventional engine isreplaced by two series of chambers, a first series and a second series,each series of chambers being separately disposed in a circumferentialarrangement about a common axis and separated in space one from another;and

(ii) wherein the conventional piston is replaced by one or more vanes,said vanes being adapted to form sealing contact with the chambers; and

(iii) the two series of chambers being connected by one or more transferports;

characterized in that air is compressed in one series of chambers andcombustion gasses are exhausted by means of the other series ofchambers.

According to a second aspect of the invention, in its broadest sense,there is provided an internal combustion engine, designed to convertthermal energy into mechanical energy according to the same generalprinciple employed in conventional reciprocating piston-and-cylindercombustion engines, wherein:

(i) the equivalent of the cylinder of the conventional engine isreplaced by two series of chambers, a first series and a second series,each series of chambers being separately disposed in a circumferentialarrangement about a common axis and separated in space one from another;and

(ii) wherein the conventional piston is replaced by one or more vanes,said vanes being adapted to form sealing contact with the chambers; and

(iii) the two series of chambers being connected by one or more transferports;

characterized in that ignition of compressed air/fuel mixture isinitiated in the transfer port.

In a first preferred embodiment according to the first and secondaspects of the invention there is provided an internal combustion enginecomprising:

(i) a casing;

(ii) at least three discs, said discs being aligned on a common axispassing through the center of the flattened face of each disc (i.e thediscs are stacked side by side or one on top of each other), the outerdiscs being fixed with respect to each other and rotatable with respectto the inner disc, which inner disc is preferably fixed;

(iii) a parallel-sided groove formed in the circumference of the twoouter discs, said groove having a constant width profile and beingadapted such that it exists in either one or other of the discs but notboth, other than during a transitional period while the groove traversesfrom one outer disc to the other, said groove thus forming two series ofchambers the first series being in the periphery of one outer disc andthe second series being in the periphery of the other outer disc, thetwo series being separated by at least one inner disc;

(iv) a vane substantially the same width as the groove, said vane beingconstrained within a slot in the perimeter of the inner disc, said vanethus being fixed in relation to the direction of rotation of the outerdiscs, and said vane being adapted such that the vane can move from sideto side in the slot to follow the path of the parallel-sided groove asit moves from one outer disc to the other;

(v) at least one inlet and one outlet port, preferably located in theengine casing;

(vi) at least one transfer port, also preferably located in the enginecasing;

(vii) an ignition source, preferably a spark plug, and preferablylocated in the transfer port.

In a second preferred embodiment there is provided an internalcombustion engine of the aforementioned type comprising;

(i) a disc mounted within a casing, the disc being rotatable withrespect to the casing;

(ii) two series of elongate chambers formed in the circumference of thedisc, the chambers of each series being located in end-to-end alignmentand the two series being spaced apart on the circumferential perimeterof the disc;

(iii) at least one vane for each series of chambers, said vanes beingconstrained in the casing such that the vane can move radially towardsand away from the disc to form a sealing contact with the chambers asthey pass by;

(iv) at least one inlet and one outlet port, preferably located in theengine casing;

(v) at least one transfer port, also preferably located in the enginecasing;

(vi) an ignition source, preferably a spark plug, and preferably locatedin the transfer port.

In a third preferred embodiment there is provided an internal combustionengine comprising;

(i) a disc mounted within a casing, the disc being rotatable withrespect to the casing;

(ii) two series of elongate chambers formed in the inner circumferenceof the casing, the chambers of each series being located in end-to-endalignment, the two series being spaced apart on the innercircumferential perimeter of the casing;

(iii) at least one vane for each series of chambers, said vanes beingconstrained within the disc such that the vanes can move radiallytowards and away from the casing;

(v) at least one inlet and one outlet port, preferably located in theengine casing;

(vi) at least one transfer port, also preferably located in the enginecasing;

(vii) an ignition source, preferably a spark plug, and preferablylocated in the transfer port.

In a fourth preferred embodiment there is provided an internalcombustion engine comprising:

(i) a casing;

(ii) a disc;

(iii) an inner ring concentric with and surrounding the perimeter of thedisc;

(iv) an outer ring, concentric with both the inner ring and the disc andsurrounding the outer ring, the disc and outer ring being fixed withrespect to each other and rotatable with respect to the inner ring, saidouter ring preferably forming part of the engine casing;

(v) a groove formed in the outer circumference of the disc and the innercircumference of the outer ring, said groove having a constant widthprofile and being adapted such that it exists in either the disc or theouter ring but not both, other than during a transitional period whilstthe groove traverses from the disc to the outer ring or vice versa, saidgroove thus forming two series of chambers the first series being in thedisc and the second series being in the outer ring, the two series beingseparated by the inner ring;

(vi) a vane substantially the same width as the groove, said vane beingconstrained within a slot in the inner ring, said vane thus being fixedin relation to the direction of rotation of the disc and the outer ring,and said vane being adapted such that the vane can move from side toside in the slot to follow the path of the parallel-sided groove as itmoves from the disc to the outer ring and back again;

(vii) at least one inlet and one outlet port, preferably located in theengine casing;

(viii) at least one transfer port, also preferably located in the enginecasing;

(ix) an ignition source, preferably a spark plug, and preferably locatedin the transfer port.

In a fifth preferred embodiment there is provided an internal combustionengine of the aforementioned type comprising;

(i) a casing;

(ii) a disc, the disc being rotatable with respect to the casing;

(iii) two series of grooves formed in the face of the disc as opposed toits periphery, the first series of grooves and the second series ofgrooves being formed respectively in two substantially concentriccircles, the centre of the circles being the rotational axis of thedisc, such that in combination with the casing these grooves form twoseries of chambers separated radially outwardly from each other;

(iv) at least one vane for each series of chambers, said vanes beingconstrained in the casing such that the vanes can only move in adirection parallel to the rotational axis of the disc;

(v) at least one inlet and one outlet port, preferably located in theengine casing;

(vi) at least one transfer port, also preferably located in the enginecasing;

(vii) an ignition source, preferably a spark plug, and preferablylocated in the transfer port.

Preferably the vane comprises a series of vane elements in substantiallyparallel, non-coaxial, corresponding end alignment.

Preferably the vane is formed from two or more vane portionscharacterised in that in use one or more of the portions are positivelyforced into sealing contact with the chamber surface.

Preferably the positive force is exerted by means of a spring.

In a particularly preferred embodiment the positive force is exerted bymeans of hydraulic pressure where the hydraulic fluid is preferably oil.

In a further preferred embodiment the vane takes the form of a pivotedcam adapted to form a sealing contact with and to follow the contours ofthe chambers.

The vane may also be formed from one or more hinged flaps adapted toform a sealing contact with and to follow the contours of the chambers.

In a still further embodiment the vane, rather than merely following thecontours of the chambers, is positively forced into sealing contact withthe chamber walls and is moved so as to follow the chamber contours,movement of the vane being achieved by means of a drive mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be moreparticularly described by way of example, with reference to theaccompanying drawings, wherein FIGS. 1 to 9 relate to a first preferredembodiment;

FIG. 1 shows a diagrammatic cross-sectional view of an engine casing andconcentric discs according to the invention;

FIGS. 2A and 2B are side and top views, respectively, of the perimeterof three circular discs incorporating a groove;

FIGS. 3A and 3B are side and top views, respectively, of a section ofthe casing around the perimeter of three circular discs as shown inFIGS. 2A and 2B;

FIG. 4 shows schematically a portion of the perimeter of three discs anda groove traversing between the discs;

FIG. 5 shows schematically a portion of the perimeter of three discs ina different part of the internal combustion cycle.

FIGS. 6A and 6B show two possible arrangements of vanes andmulti-component spring-loaded systems (FIG. 6B) for use as vanes;

FIGS. 7, 8 and 9 show more detailed cross-sections of a further versionof the first preferred embodiment;

FIGS. 10A and 10B show two cross-sectional views of a second preferredembodiment having spring-loaded vanes and FIGS. 10C and 10D show twocomparable cross-sectional views of a second preferred embodiment usinghydraulic fluid-pressured vanes;

FIGS. 11A and 11B show two cross-sectional views of a third preferredembodiment;

FIGS. 12A and 12B shows two cross-sections views of a fourth preferredembodiment; and

FIGS. 13A and 13B shows two cross-sectional views of a fifth preferredembodiment;

FIG. 14 shows a series of vanes in the form of pivoting cams;

FIG. 15 shows a series of vanes in the form of pivoting flaps; and

FIG. 16 shows a diagrammatic cross-sectional view of a plurality ofengines according to the invention mounting in series on a single shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The embodiments shown in FIGS. 1-16 represents currently the best waysknown to the applicant of putting the invention into practice.

Reference will be made, wherever possible, to the equivalent parts of aconventional internal combustion engine.

FIG. 1 shows schematically the elements of an engine according to afirst preferred embodiment of this invention. It illustrates threeconcentric discs 10, 11 and 12 which are housed within a casing 13 whichin turn has apertures 14 and 15 through which a combustion mixture andexhaust gases can enter and exit respectively. The casing is equivalentto an engine block in a conventional engine. The portion of the casingengine 16 around the perimeter of the discs 10-12 corresponds to aconventional cylinder head.

The basic concept is as follows. The inner disc 12 is fixed and oneither side of the inner disc are located two, outer rotatable discs 10and 11. The outer discs are locked together such that they rotate as asingle entity. This can conveniently be achieved by means of a driveshaft 17 that sits in a bearing (not shown) in the fixed disc 12. Itwill therefore be appreciated that the casing 13 and inner disc 12 arefixed in relation to one another and the outer discs 10 and 11 rotateabout a central shaft.

The channel 18 is formed only in the periphery of the discs 10 and 11,which in turn are encased within the housing 16. The diameter of theinner disc is at least as great as the two outer discs and thus it formsa gas-tight barrier between those parts of the channel on one side, 18A,18C and 18E (series one) and those parts of the channel on the oppositeside of the disc, namely 18B and 18D (series two). This creates what isin effect two series of chambers, one series being located entirely inthe periphery of one outer disc and the other series being in the other.

The term disc in this context has a broad meaning. Clearly the perimeterof each disc must be substantially circular in order that it can rotatewithin the engine casing 16. The various discs must also be a mating fitat their perimeter, as shown in FIG. 1, in order to create asubstantially gas-tight channel. The remainder of the disc can take awide variety of shapes and configurations. For example, it is likelythat cooling and lubrication would be needed in the internal region ofeach disc, particularly on the side of the engine where combustion gasesare exhausted (see below). This will require cooling and lubricationports as well as some form of circulation system. It is envisaged thatboth air, water and oil cooled versions will be produced, depending onthe use to which the engine is going to be put. The discs can thereforebe flat-faced as with a stack of washers, for example, or hollowed i.edished.

In the circumference of the rotatable outer discs is what amounts to aparallel-sided groove or channel 18. This groove has a fixed width andis adapted such that the groove may exist in either of the outer discsbut not in both, except where it traverses from one disc to another.

The profile of the groove is likely to affect the performance anddurability of the engine and this description is intended to cover allpossible profiles.

The fixed disc 12 contains vanes 19 which are retained in slots 20 inthe perimeter of disc 12. The vanes extend fully across the width anddepth of the groove 18 and form a substantially gas-tight barrier. Thevanes are fixed in relation to the direction of the rotation of theouter discs but may move freely within the groove to follow the courseof the groove as it traverses from one rotatable disc to another. Aswell as being supported by disc 12 the vanes also extend into and arefurther supported by the casing 16.

In a conventional engine, these vanes would correspond to the pistons.It will be appreciated therefore that these vanes can have a very lowmass and thus the inertia of the reciprocating element in this new typeof engine is also low.

As previously described the inner disc 12 provides a gas-tight sealbetween one series of chamber and the other. However, there arespecifically adapted connecting ports called transfer ports shown as23A, 23B & 23C in FIGS. 4 & 5. The transfer ports are formed in thecasing 16 and create a direct connection between the inlet side of theengine and the exhaust side. They are also where ignition is initiated,generally by means of a spark plug supported in the casing. The functionof these transfer ports will be revealed by the description of thecombustion cycle below.

An outer ring or casing 16 is secured around the three discs 10-12. Ineffect, the casing in its entirety comprises two fixed discs 13A and 13Btogether with an outer ring 16 which fits over all five discs. Thisouter ring provides mechanical support for the previously describedcomponents.

The combustion cycle will now be described in detail with reference toFIGS. 4 and 5. These depict a portion of the groove 18 in various stagesin the process and in which a variety of cavities or chambers arecreated as the groove sweeps past the static vanes. These stages are:

1. FIG. 4

Chamber A is enlarging drawing fuel air mixture into it.

Chamber B is decreasing compressing the fuel air mixture into transferport 23B, note right hand side of 23B is closed. Fuel/air mixture canenter the transfer port but cannot escape because the other end of theport is sealed.

Chamber D is decreasing pushing exhaust gases out of exhaust port 22A.

Chamber F is expanding under the pressure of the ignited gases expandingfrom transfer port 23C and into chamber F.

Note transfer ports 23A and 23C are both in the firing cycle i.e. bothsides of the vane are active at all times.

2. FIG. 5

Chamber A is just starting to open about to start an intake cycle.

Chamber B is fully open and full of fuel/air mixture bottom dead centrein conventional terms (BDC)!.

Chamber C is fully compressed with fuel/air mixture compressed intotransfer port 23B and therefore into chamber F and is ready for ignitionand subsequent expansion into chamber F top dead center in conventionalterms (TDC)!.

Chamber D is fully expanded (BDC) and about to start an exhaust cycle.

Chamber E is fully closed after an exhaust cycle.

This cycle is repeated around the perimeter of the discs.

This particular embodiment of the engine is shown in more detail inFIGS. 7, 8 and 9. These show a three vane-two chamber version. In thiscontext therefore a series of chambers can include just a single chambere.g 104 divided by one or more vanes.

A number of features will have become apparent from the foregoingdescription. For example, the compression cycle always takes place inone series of chambers on the same side of the engine, i.e in theperiphery of one disc in this example. Conversely the power stroke takesplace in the opposite disc. This brings with it a number of advantages,firstly, alternate heating and cooling is avoided, each disc running ata fairly constant temperature. As well as avoiding rapidexpansion/contraction it also means that special arrangements can bemade to remove heat from the exhaust side of the engine.

Secondly it is no longer necessary for the compression stroke and thepower stroke to be the same volume. They can be varied independently andpractically at will, simply by changing the size, shape, length and/ordepth of the chambers on each side of the disc. The transfer ports mayneed to be angled or staggered accordingly but this is a relativelysimple matter.

Firing can now take place at TDC unlike in a conventional engine whereit usually occurs some 10° to 20° before TDC, thus increasing outputsince the full force of the explosion is used to propel the vane.

The power stroke is applied tangentially to the periphery of a rotorleading to optimum power use.

By allowing combustion to start in a transfer port the full range ofcarburation/fuel injection/diesel options are possible. That is to say,fuel may be introduced along with air in a carburetor aspirated version.Alternatively fuel can be injected into the compression chamber at anappropriate point. High pressure fuel injection can be used to injectfuel directly into the transfer port just prior to ignition.

The internal shape of the transfer port is important in achievingcomplete combustion and the techniques applied in conventional gasolineengines may also be applied here. Conventional spark plugs can be usedto initiate combustion of the fuel/air mixture in a similar manner toconventional engines. Timing of the ignition spark can also be achievedby conventional means.

The arrangement of discs and chambers described above is just one of themany possible configurations. Alternatives are shown in FIGS. 10-13inclusive.

FIGS. 10A and 10B shows an arrangement whereby the two series ofchambers 1-4 are arranged side by side but spaced apart in the perimeterof a single disc 121. Rather than traversing at right angles to thedirection of rotation of the disc, the vanes in this example moveradially towards and away from the output shaft, riding up and down onthe base of the channels. The vanes are maintained in contact with thechannels by spring-loading (FIGS. 10A and 10B) or hydraulic pressure(FIGS. 10C and 10D) which can be applied by conventional means, thevanes being held in a static housing.

FIGS. 11A and 11B shows the inverse of this arrangement wherein thevanes are retained in an inner disc 171 and the channels are located inthe inner surface of the outer housing 176.

A further preferred embodiment is illustrated in FIGS. 12A and 12B. Inthis example an inner 131 and an outer 133 disc rotate together on anoutput shaft and a stator 132 separates the two rotating discs. Thestator, or fixed disc 132, contains vanes 135 which are retained inslots not dissimilar to those described in FIGS. 1-5. One series ofchambers is formed in the outer disc 133 and a complimentary series ofchambers is formed in the inner disc 131. Once again the vanes movedradially towards and away from the output shaft.

FIGS. 13A and 13B illustrates an arrangement whereby two series ofchambers 144 are formed in the face of a disc, rather than in itsperiphery. The chambers take the form of a series of grooves arranged intwo concentric circles, the center of each circle being the outputshaft. Each vane in this example consists of two vane portions 145operating independently. Once again the vanes are maintained in sealingcontact with the chambers by spring or hydraulic pressure.

These are just some of the permutations possible with this invention butthere are others which have not been illustrated here. Each exampleincorporates the necessary number of inlet and outlet ports, a transferport associated with each vane or set of vane portions, and an ignitionsource associated with each transfer port.

These examples further serve to illustrate the broad meaning of the termdisc in this specification. This term is intended to encompass anyrotatable or static member which can accommodate channels or vanes.

Although not specifically illustrated it is possible to vary therelative juxtaposition of the compression and exhaust chambers and thusalter the timing and power output of the engine. This provides a furtheroption not available in a conventional engine design.

The number of chambers in each series and the number of vanes can bevaried to suit the requirement of a particular engine and have a directbearing on the performance on the engine. The rotating chamber profilealso have a significant influence on:

a) operation of the sealing vanes;

b) port timings;

c) size of the engine.

The ramping angle profile of the cavities provide the effort required tooperate the sliding vanes. If the angle is too large then a high loadwill be inparted to the vane tip resulting in high friction of theinterfaces and bending moments together with a high reciprocatingvelocity of the vane.

The ramping angle also controls the timing events of the engine'soperating cycles. These events will also depend upon the profile of theports located in the outer casing of the engine. The cavitycross-sectional profile can be configured in various proportions andshapes. The selected shape influence a number of parameters such as:

overall size of the engine;

number of cavities;

stroke of vanes;

size and shape of ports.

As with all current engines the effectiveness of the sealing of itschambers containing the working gases is one of the keys to an efficientengine design. This applies to conventional reciprocating piston androtary engines. Dynamic sealing is one of the most demanding tasks,having to contend with the forces generated by velocity and accelerationof the seal and its interfacing components. This particular enginerequires a number of dynamic seals to be maintained for efficientoperation.

Sealing of the vanes, to retain the gases and pressures has to beaccomplished around the profile of the rotating channel formed in thediscs. The channel cannot be fully circular and therefore the sealingelements have to be capable of exerting a force at the interfaces ofvanes, channel and possibly stator slots. The sealing faces of the vanealso have to accommodate a rubbing/reciprocating action which, dependingupon the size of the engine, could result in high velocities andaccelerations. This can be achieved in a number of ways and it must alsobe remembered that the slider-type vane must have the necessaryresilient properties to follow the contours of the groove 18 as well asbeing hard-wearing. Optionally, the vane can be constructed from aseries of parallel vane elements 24 as illustrated in FIG. 6. The vaneelements are free to move parallel to each other and this arrangementhas the advantage of reducing both friction and the wear as the vane 19follows the traversing groove 18.

In a further option the vane or vane components can be made in two ormore portions, which meet in the plane of the fixed disc 12. Theportions are forced apart, and thus into contact with the walls of thegroove, by a spring or other elastomeric component or by lubricantpressure. In this way it is possible to compensate for the inevitablewear that takes place in use at the end of the sliders.

Various alternative vane constructions are shown in FIGS. 14 and 15.FIG. 14 shows a series of cams 155, pivoted towards one end about pivot158, such that the cams can swing from side to side so as to follow thecontours of the channel 154 as it traverses from disc to disc asdescribed in the first preferred embodiment. This offers a number ofadvantages. Firstly a cam is inherently better able to withstand thepressures and forces experienced inside an engine. Secondly, sealingelements 59 can be incorporated at strategic points into the cam andthese can be spring or hydraulically loaded into sealing contact withthe chamber walls.

If necessary, provision can also be made to drive these cams such thatthey positively follow the path of the channel rather than simply beingguided by its course although this will, of necessity, lead to a morecomplex engine design.

A further variant is shown in FIG. 15 which depicts an alternative formof pivoted vane. In this example a vane 165 is pivoted about a pivot168, the pivot point being within the static disc 162. The vanes arespring-loaded by springs 69 to encourage sealing contact with the sidesof the channels. In effect, a vane 165 has been split into two vaneportions 165A and 165B operating independently of each other. Thisenables each vane portion to be positioned at the optimum contact anglewith respect to the channel wall.

This entirely new concept in engine design brings with it a number ofimportant advantages. Firstly, the diameter of the discs, i.e therotating part of the engine can be kept relatively small. Thus theentire power unit can be small in both size and weight. Such an enginewill find new applications in, for example, small domestic garden toolssuch as strimmers where petrol-engined versions have previously onlybeen employed in industrial-type units.

Equally importantly, by keeping the radius of the discs small thesliding/rubbing velocity between the disc and stator is smaller than itwould otherwise be. This reduces the heat generated at the seals whichin turn reduces the possibility of friction welding. In effect thesmaller the diameter of the rotating disc(s) the higher the maximum rpmof the engine. Secondly, if a more powerful engine is required this canbe achieved simply by incorporating additional units onto the sameoutput shaft. As shown in FIG. 16, each engine module is in effect aself-contained unit and as many as necessary can be linked in series forany given application. Thus, it is theoretically possible to produce astandard engine module and simply combine any number of these togetherto obtain the necessary performance for a particular application. Thishas obvious advantages over the current situation where a carmanufacturer for instance produces a whole series of different enginesto power a range of vehicles.

The precise details needed to put the invention into practice will forman inevitable part of the common general knowledge of the intendedskilled addressee of this specification.

We claim:
 1. An internal combustion engine comprising:(i) a casing; (ii)a least three discs, said discs being aligned on a common axis passingthrough the center of the flattened face of each disc, the outer discsbeing fixed with respect to each other and rotatable as a single entitywith respect to the inner disc; (iii) a parallel-sided groove formed inthe flattened face of the two outer discs, said groove having a constantwidth profile and being adapted such that it exists in either one orother of the discs but not both, other than during a transitional periodwhile the groove traverses from one outer disc to the other, said groovethus forming two series of chambers, the first series being in theflattened face of one outer disc and the second series being in theflattened face of the other outer disc, the two series being separatedby the inner disc; (iv) a vane substantially the same width as thegroove, said vane being constrained within a slot in the perimeter ofthe inner disc, said vane thus being fixed in relation to the directionof rotation of the outer discs, and said vane being adapted such thatthe vane can move from side to side in the slot to follow the path ofthe parallel-sided groove as it moves from one outer disc to the other;(v) at least one inlet and one outlet port, located in the enginecasing; (vi) at least one transfer port located in the engine casing,adapted to connect the first and second series of chambers; (vii) anignition source located in said at least one transfer port forinitiating ignition in said at least one transfer port;the inner discand the casing being static in relation to each other such that, in use,the two outer discs rotate with respect to the inner disc and withrespect to the casing.
 2. An internal combustion engine as claimed inclaim 1 wherein the vane comprises a series of vane elements insubstantially parallel, noncoaxial, corresponding end alignment.
 3. Aninternal combustion engine as claimed in claim 1 wherein the vanecomprises a plurality of vane portions and means for positively forcingat least one of said portions into sealing contact with the chambersurface.
 4. An internal combustion engine as claimed in claim 1 whereinthe vane takes the form of a pivoted cam adapted to form a sealingcontact with and to follow the contours of the chambers.
 5. An internalcombustion engine as claimed in claim 1 wherein the vane is formed fromone or more hinged flaps adapted to form a sealing contact with and tofollow the contours of the chambers.
 6. An internal combustion engine asclaimed in claim 1 wherein the vane, rather than merely following thecontours of the chambers, is positively forced into sealing contact withthe chamber walls and is moved so as to follow the chamber contours,movement of the vane being achieved by means of a drive mechanism.
 7. Aninternal combustion engine comprising a plurality of engines as claimedin claim 1 mounted in series on a single shaft, the power output fromthe combination being substantially the sum of the power output fromeach individual engine.
 8. An internal combustion engine as claimed inclaim 1, wherein said ignition source is a spark plug.
 9. An internalcombustion engine as claimed in claim 3, wherein said means forpositively forcing comprises hydraulic fluid.
 10. An internal combustionengine as claimed in claim 9, wherein said hydraulic fluid is oil. 11.An internal combustion engine as claimed in claim 3, wherein said meansfor positively forcing comprises spring means.